Electromagnetic device



Jan. 12; 1943. DICKTEN, JR

- ELECTROMAGNETIC DEVICE Filed May 1, 1941 FIG. 7

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ATTORNEY Patented Jan. 12, 1943 U NITED STATES PAT ENT OFFICE Telephone Laboratories, Incorporated,

New

York, N. Y., .a corporation of New York Application May '1, 1941, Serial No. 391,323

3 Claims.

This invention relates to electromagnetic devices and more particularly to devices which are polarized to be responsive to current of but one polarity. The invention is a continuation in part of my application Serial No. 344,900, filed July 11, 1940.

The object of the invention is to enable the modification of neutral relays or electromagnetic devices in a simple manner to render them selectively responsive to energizing current of a predetermined polarity.

This object is attained by bridging a portion of the magnetic circuit of the electromagnetic device by a permanent magnet thereby forming a magnetic rectifier which admits the'fiow of magnetic flux to enable the device to operate when energizing current of a predetermined polarity is applied to the operating coil of such device-and which impedes the flow of magnetic flux toprevent the operation of the device when energizing current of the opposite polarity is'applied to the operating coil. In accordance with the invention the permanent magnet bridge is applied between the forwardend of the core and the return pole-piece.

For a more comprehensive understanding of the invention, reference may be had to the following detailed description taken in connection with theaccompanying drawing inwhich:

Fig. -1 is a perspective view partly in cross .section of a message register modified-inaccordance with the present invention;

Fig. 2 is a detail view of the arrangement of the permanent magnets'disclosed in Fig. 1;

Fig. 3 is a top-plan view of a conventional type of relay to which the presentinvention has been applied;

Fig. '4 is a front end view of "the-relay disclosed in Fig. 3;

Fig. 5 is a perspective view of the wedging spring detail shown in Fig. 3;

Fig. 6 is a perspective view of thepermanent magnet shown in Fig. 3; a

Fig. '7 is a partial end view of a relay of the type disclosed in Fig. 3 showing a supporting cradle for the permanent-magnet; and,

Fig. 8 is a top 'view of the supporting cradle shown in Fig. 7.

Referringfirst to Figs. 1 and 2, the invention has been illustrated as applied to a subscribers message register of well-known construction. The register is provided with a U-shaped return pole-piece I having legs 2 and 3 and to the base of which a core 4 is secured which extends forwardly between the legs 2 and 3. Theron is provided with a rear threaded portion 5 which extends througha hole in the base of the return pole-piece and upon which a nut 6 is threaded for clamping the core to the pole-piece. Mounted upon the core is an operating coil 1 having rear and ,forward spoolheads 8 and 9. Secured by screws 10 between the forward ends of the legs 2 and 3 .of the return pole-piece is a plate H of non-magnetic material having .a central hole through which theend of the core 4 extends, and which serves to hold the ends of the legs in the proper .spaced relationship with the end of the core.

Positioned between the plate II and the forward spoolhead 9 and between the forward end of the core 4 and the inside surfaces of legs 2 and 3.01" the return pole-piece are 'two short bar magnets l2. .For this purpose the end of the core is provided with notches l3, as best disclosed in Fig. 2, in which the inner and corresponding polar ends of the magnets l2 are seated. An armature is pivoted between the forward ends of the legs v2 and 3 of the return pole-piece for cooperation with the forward end of the core 4 and with the forward ends of the legs 2 and 3. A-mounting member I4 for the message register mechanism is also secured to the forward end of the legs 2 and 3 by the screws l5, such mechanismbeing positioned beneath the dust cover [6.

By means of the magnets [-2, parallel permanent magnet shunts are established around the portion of the core 4 on which the coil 1 is mounted, .one of which shunts extends from the forwardend of the core through one of the magnets l2 and the leg 2 of the return pole-piece to the rear end of the core and the other of which shunts extends from the forward end of the core through the other of the magnets 12 and the leg 3 of the returnpole-piece to the rear end of the core. With the permanent magnets connected asdisclosed, a flow of fiux is set up in the core 4 which may be visualized as leaving the north poles of the magnets, flowing rearwardly through the legs 2 and 3 of the return pole-piece, fiowing forwardly through the core 4 and then entering the south poles of the magnets.

If current of a predetermined polarity is now applied to coil 1, a-coil flux will be set up in the core 4 which will flow rearwardly through the core returning through the legs 2 and 3 of the return pole-piece and across the air-gaps between the ends of the pole-piece legs and the armature, through the armature and across the air-gap between the armature and the forward end of the core. The coil flux will therefore oppose the permanent magnet flux in the core 4 and the fiux density in the core is therefore decreased whereby flux readily flows across the air-gaps between the ends of the pole-piece legs and armature and between the armature and the end of the core, whereupon the armature becomes attracted to the core. I

If current of the opposite polarity is applied to the coil i, a coil flux will be set up in the core 4 which will tend to flow forwardly through the core and thus aid the permanent magnet flux, but since the core 4 is almost or entirely saturated with their inner ends engaged against the fordue to the Iiux from the permanent magnets I2, I the increase in flux in the core will beslight orv nil and practically no flux will flow across the air-gaps and therefore the armature will be unaffected.

Figs. 3 to 8 inclusive, show the invention ap plied to a relay structure of a well-known type. In general this relay comprises a T-shaped core member i'i upon the shank portion of which a coil i8 is supported and to the crosspiece IQ of which are secured two similar sheet iron punchings 2t and 2 l, each of which has an ear 23 bent at right-angles from each end thereof and an intermediate ear The four ears 23 serve as supports for the tubular casing 22 which may be secured thereto by screws extending through holes in the casing into threaded holes 25 in the ears 23 andthe ears 2% serve as brackets by means of which the relay may be secured to a relay mounting plate.

Mounted upon the shank portion 11 of the core, near the outer extremity thereof and adjacent the front spoolhead 26 of the coil I8, is a supporting plate 2?. This plate is mounted at rightangles to the core and its periphery substantially fills the space within the inner walls of the casing 22 and prevents relative movement between the forward ends of the core and casing. The armature 28 is formed from a substantially U-shaped punching of magnetic material comprising a yoke piece 29 overlying the forward end of the core and two rearwardly extending side arms riveted at their rear ends to the forwardly ex tending arms of a resilient spring hinge 30. The spring hinge is clamped between the rear crosspiece portionifi of the core and the punching 20.

Mounted upon the punchings 2B and 21, respectively, and insulated therefrom are secured the forwardly extending contact springs 3| to 34, inclusive, arranged in two sets, the springs of each set due to their resiliency and formation tending to spring away from each other at their forward ends. The contact springs. of each set are located on either side of the armature 28 which is arranged to operate between them. Carried by the outer end of each contact spring is a contact point which cooperates with a contact point carried by the end of the armature. As shown in Fig. 4, the contact springs as well as the side arms of the armature project forwardly through cut-out portions of the plate 27. Strips of insulating material (not shown) serve in the well-known manner to insulate the contact springs and the coil terminal lugs and 36 from each other and from the punchings 2i) and 2|,

The contact springs are provided with rearwardly extending soldering lug extensions 31 and 38 and a terminal lug 39 is clamped in conductive engagement with the core and thus with the armature 28.

For adjusting the positions of the forward ends of the contact springs with respect to the armature 28, backstop screws it to 13, inclusive, are

ward angular portions of the springs. For example, screw 48 engages against portion 44 of spring 3| and screw GI engages against the angular portion d5 of spring 32. The ends of the screws at their points of engagement with the springs are provided with insulating tips.

Positioned between the side wall 46 of the casing 22 and th adjacent face of the forward end of the core ii is a short bar magnet 47 which electromagnetically connects the core I! to the casing ,22 which is also of magnetic material. The permanent magnet thus completes a shunt around that portion of the core I! on which the coil [8 is supported and causes the relay to operate its armature only when current is transmitted through its coil in a predetermined direction in the manner previously explained in connection with the messageregister of Figs. 1 and 2. To insure that the permanent magnet t! will make good bridging contact between the core I! and the casing 22, a U-shaped leaf spring 48 is inserted between the outer side wall 19 of the casing and the adjacent edge of the plate 27 to wedge the end of the core ll toward the opposite side wall 46 of the casing. With this structure, it is not possible to use the usual cap closure for the relay casing 22 since the flanges of the cap which fit against the inner surfaces of the side walls 46 and 49 of the casing are obstructed by the wedging spring 48 and the bar magnet 41.

As an alternative structure, to permit the use of the usual closure cap, the bar magnet 41 may be supported in. a cradle 56 of spring material of substantially the form disclosed in Figs. 7 and 8. The cradle has a central box-shaped portion comprising side Walls 5|, 52 and 53 and a bottom wall 54 within which the magnet 41 is supported, and is provided with two wing portions 55 and 56. The wing portions are provided with holes through which the backstop screws 4| and 43 may extend. To assemble the magnet and cradle on'the relay, the magnet is placed in the box portion of the cradle and the ends of the wings 55 and 56 of the cradle are then sprung slightly toward the outer face of plate 27 by pressure on the tabs 51 and 58, struck up therefrom, thus shortening the distance between the centers of the holes in the wings 55 and 56 until such holes are aligned with the ends of the screws M and 43. The cradle is then pressed back against the forward face of the plate 21 and, when the pressure on the tabs is released, the straightening out of the cradle wings will establish a firm grip on the ends of the screws to hold the cradle in its assembled position with the free end of the magnet 41 magnetically engaged against a face of the end of the core l1. It willbe noted that the bottom wall 54 of the box portion of the cradle is separated sufnciently from the inner face of the wall 46 of the cover to permit thev entry of a flange of a closure cap between such wall and the easing and since no wedge is required between the edge of the plate 27 and the opposite side wall of the casing no obstruction is offered to the entry of a further flange of the cap against the inner surface of the opposite wall of the casing. Although the end of magnet 4! which is engaged against the bottom Wall 54 of the cradle 50 is not in magnetic engagement with the wall 46 of the casing 22, the air-gap-between suchend of the magnet and the wall 46 of the casing is sufiiciently narrow to enable the magnet 41 to effect a permanent magnetic shunt between the outer end of the core I! and. the outer end of the casing 22 around that portion of the core I! upon which the coil 18 is supported and thereby causes the relay to operate its armature only when current is transmitted through its coil in a predetermined direction.

What is claimed is:

1. In a relay, a core, supporting brackets of magnetic material secured to the rear end of said core, a coil on said core, an armature hinged to the rear end of said core and attractable to the forward end of said core, a tubular cover of magnetic material secured to said brackets and extending forwardly over said coil and a permanent bar magnet magnetically connecting the forward end of said core and one wall of said cover to provide a magnetic shunt of that portion of said core on which said coil is supported whereby said armature is attracted toward said core only when said coil is energized by current of a predetermined polarity.

2. In a relay, a core, supporting brackets of magnetic material secured to the rear end of said core, a coil on said core, an armature hinged to the rear end of said core and attractable to the forward end of said core, a tubular cover of magnetic material secured to said brackets and extending forwardly over said coil, a permanent bar magnet interposed between the forward end of said core and one wall of said cover to provide a magnetic shunt of that portion of said core on which said coil is supported whereby said armature is attracted toward said core only when said coil is energized by current of a predetermined polarity, and means for holding one polar end of said magnet in engagement with one face of the forward end of said core.

3. In a relay, a core, supporting brackets of magnetic material secured to the rear end of said core, a coil on said core, an armature cooperating with said core, a tubular cover of magnetic material secured to said brackets and extending forwardly over said coil, a plate of non-magnetic material secured to the forward end of said core with its edges extending substantially into engagement with the walls of said cover, a permanent bar magnet interposed between the forward and of said core and one wall of said cover whereby said armature is attracted toward said core only when said coil is energized by current of a predetermined polarity, and a wedge of resilient material interposed between one wall of said cover and an edge of said plate for pressing the forward end of said core toward the opposite wall of said core cover to firmly embrace said magnet between said core and said wall.

EMIL DICKTEN, JR. 

